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  1. /*/ 
  2. 	 Author: _Chaitanya1999
  3. 	 "Everything in this world is magic, except to the magician"
  4. /*/
  5. #include<bits/stdc++.h>
  6. using namespace std;    
  7.  
  8. /*/---------------------------Defines-----------------------------------------/*/
  9.  
  10. #pragma GCC optimize("Ofast") 
  11. #define int long long
  12. #define IOS ios_base::sync_with_stdio(false);cin.tie(NULL);
  13. #define pb push_back 
  14. #define eb emplace_back
  15. #define fn for(int i =0 ;i <n;i++)  
  16. #define fn1 for( int i =1;i<=n; i++)
  17. #define fm for(int j =0 ;j <m;j++)
  18. #define fm1 for(int j =1;j<=m;j++)
  19. #define fi first
  20. #define se second
  21. #define endl '\n'
  22. #define PI  3.14159265358979323846
  23. #define MOD 1000000007
  24. #define all(a) a.begin(),a.end()
  25. #define rall(a) a.rbegin(),a.rend()
  26. const int N = 2e6+5;    
  27. const int INF = 1e18L;
  28. // for all eight directions
  29. int dx[8] = {-1, -1, -1, 0, 1, 1, 1, 0};
  30. int dy[8] = {-1, 0, 1, 1, 1, 0, -1, -1};
  31. // for all 4 directions
  32. //int dx[4]={-1,1,0,0};
  33. //int dy[4]={0,0,-1,1};
  34. //mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
  35. /*/-----------------------------Debug begins----------------------------------/*/
  36. vector<string> split(const string& s, char c) {
  37.   vector<string> v; stringstream ss(s); string x;
  38.   while (getline(ss, x, c)) v.emplace_back(x); return move(v);
  39. }
  40. template<typename T, typename... Args>
  41. inline string arrStr(T arr, int n) {
  42.   stringstream s; s << "[";
  43.   for(int i = 0; i < n - 1; i++) s << arr[i] << ",";
  44.   if(n>0)
  45.   s << arr[n - 1] ;
  46.   s<< "]";
  47.   return s.str();
  48. }
  49. #define trace(args...) {__trace_begin(__LINE__); __trace(split(#args, ',').begin(), args);}
  50. inline void __trace_begin(int line) { cerr << "#" << line << ": "; }
  51. template<typename T> inline void __trace_out_var(vector<T> val) { cerr << arrStr(val, val.size()); }
  52. template<typename T> inline void __trace_out_var(T* val) { cerr << arrStr(val, 10); }
  53. template<typename T> inline void __trace_out_var(T val) { cerr << val; }
  54. inline void __trace(vector<string>::iterator it) { cerr << endl; }
  55.  
  56. template<typename T, typename... Args>
  57. inline void __trace(vector<string>::iterator it, T a, Args... args) {
  58.   cerr << it->substr((*it)[0] == ' ', it->length()) << "=";
  59.   __trace_out_var(a);
  60.   cerr << "; ";
  61.   __trace(++it, args...);
  62. }
  63. /*/-----------------------------Code begins----------------------------------/*/
  64. int ar[N];
  65. signed main(){
  66.   IOS;
  67.   int T=1;
  68.   cin >> T;
  69.   while(T--){
  70.   	int n;
  71.   	cin >> n ;
  72.   	int dp[n][3];
  73.   	fn{
  74.   		cin >> ar[i];
  75.   		dp[i][0]=dp[i][1]=dp[i][2]=0;
  76.   	}
  77.   	dp[0][0]=ar[0];
  78.   	dp[0][1]=ar[0]+1;
  79.   	dp[0][2]=ar[0]-1;
  80.   	for(int i=1;i<n;i++){
  81.   		dp[i][0]=max({__gcd(ar[i],dp[i-1][0]),__gcd(ar[i],dp[i-1][1]),__gcd(ar[i],dp[i-1][2])});
  82.   		dp[i][1]=max({__gcd(ar[i]+1,dp[i-1][0]),__gcd(ar[i]+1,dp[i-1][1]),__gcd(1+ar[i],dp[i-1][2])});
  83.   		dp[i][2]=max({__gcd(ar[i]-1,dp[i-1][0]),__gcd(ar[i]-1,dp[i-1][1]),__gcd(ar[i]-1,dp[i-1][2])});
  84.   	}
  85.   	int ans=max({3ll,dp[n-1][0],dp[n-1][1],dp[n-1][2]});
  86.   	cout << ans << endl;
  87.  
  88.   }
  89.   return 0;
  90. }
Runtime error #stdin #stdout 0s 4928KB
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https://ideone.com/EkXmYu
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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